Green tea may weaken blood pressure medication

New research suggests that in addition to avoiding grapefruit juice, people on certain blood pressure medications may want to also steer clear of green tea.

Japanese and European researchers have found that green tea can negatively interfere with the blood pressure medication called nadolol, reports BBC.

Green tea has been hailed as a natural healer for its high concentration of antioxidants, which have been linked to a reduced risk of cardiovascular disease and various types of cancer.

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But the study, published in the journal Clinical Pharmacology & Therapeutics, found that people who drank green tea while taking nadolol had lower circulating blood levels of the drug. Researchers say a compound found in the tea blocks the transportation of the drug into the body's cells, preventing the medication from taking effect.

The scientists speculate that only a couple cups of the herbal tea would be enough to see these effects.

They came to this conclusion by examining 10 healthy non-smoking adults between the ages of 20 and 30, reports the Los Angeles Times.

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All participants were given a daily 30-mg dose of nadolol -- half were instructed to drink three cups of green tea with it, and the other half drank water. After a two-week break, the groups switched to the other beverage, but continued to take the same dosage of nadolol.

The researchers found that participants who drank green tea had 76 per cent less nadolol in their blood than when they drank water.

Furthermore, the amount of nadolol detected in their urine was about 80 per cent lower after they drank green tea -- suggesting the drug wasn’t absorbed as effectively by the body.

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